Graphene oxide affects growth and physiological indexes in Larix olgensis seedlings and the soil properties of Haplic Cambisols in Northeast China

Changbai larch (Larix olgensis A. Henry) seedlings growing in a Haplic Cambisol and receiving 0 (Ck), 25, 50, 100, 250, or 500 mg L−1 graphene oxide (GO) were incubated for 30, 40, or 50 days, and the effects of applying GO on the growth and physiological characteristics of the seedlings and soil chemical properties and enzyme activities were investigated. The superoxide anion (except for 25 mg L−1 at 40 days and 50 mg L−1 at 50 days) and hydrogen peroxide contents of the leaves increased at 25–100 mg L−1 GO; however, superoxide dismutase (SOD) and peroxidase (POD) (except for 100 mg L−1 at 50 days) activities, soluble protein (except for 100 mg L−1 at 30 and 40 days), proline (except for 100 mg L−1 at 50 days), as well as seedling biomass (except for stems at 25–100 mg L−1, and leaves and roots at 50–100 mg L−1 for 30 days) all decreased. However, when the seedlings were exposed to 250–500 mg L−1 GO, especially at 40 and 50 days, these trends for tree growth and physiological parameters were reversed, suggesting the beneficial effect of GO at high concentrations on the seedlings. GO decreased the organic matter, alkali-hydrolyzale nitrogen, available phosphorus, and potassium contents of the soil at 40 and 50 days (except for available phosphorus at 50 days), as well as the acid phosphatase, urease (except for 30 days), dehydrogenase, and catalase activities (except for 30 and 40 days); thus, GO may inhibit nitrogen and phosphorus cycling in Haplic Cambisols (except for nitrogen at 30 days).